The Kiepenheuer Institute for Solar Physics is a research institute located in Freiburg, Germany. Its research focuses on the exploration of the Sun and heliosphere. The institute has one solar telescope on the Schauinsland Mountain near Freiburg and, in collaboration with other institutions, uses solar telescopes of the Teide Observatory in Tenerife, Spain. Wikipedia.

In this review we give an overview about the current state-of-knowledge of the magnetic field in sunspots from an observational point of view. We start by offering a brief description of tools that are most commonly employed to infer the magnetic field in the solar atmosphere with emphasis in the photosphere of sunspots. We then address separately the global and local magnetic structure of sunspots, focusing on the implications of the current observations for the different sunspots models, energy transport mechanisms, extrapolations of the magnetic field towards the corona, and other issues.
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